Suppose that f(x) and g(x) are functions on [a,∞), and that
0≤f(x)≤g(x) for all x∈[a,∞). Then
∫∞af(x)dx will always be better behaved than
∫∞ag(x)dx.
In particular:
-
If ∫∞ag(x)dx converges, then ∫∞af(x)dx converges.
- If ∫∞af(x)dx diverges, then ∫∞ag(x)dx diverges.
- If ∫∞af(x)dx converges, then we can't tell what happens to ∫∞ag(x)dx.
- If ∫∞ag(x)dx diverges, then we can't tell what happens to ∫∞af(x)dx.
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